1. Compounds

2. Ionic Compounds made by combination of metal and nonmetal
metal loses electrons – forms cation
nonmetal gains electrons – forms anion
consider Na and S
Na+ and S2- ions formed
pack together to make compound Na2S

3. Ionic Compounds can contain polyatomic ions like (NH4)+
consider (NH4) + and S2- ions formed
pack together to make compound (NH4)2 S +

4. NaCl Crystal Lattice

5. Properties of Ionic Compounds
high melting point
hard but brittle
cleave with flat edges
when dissolve in water, dissolves as ions
Conductors when melted or dissolved in water

8. Covalent (Molecular) Compounds
made by combination of nonmetals only
made by “sharing” electrons
make molecules…fundamental particle of compound

9. Example of a Molecule - Water

10. If have water, have water molecules

11. Pure and Polar Covalent Bonds
are electrons shared equally?
H – H and F - F
pure covalent bond
H - Cl
polar covalent bond

12. Electronegativity: A Measure of Polarity

13. Electronegativity and Bonds
Using electronegativities, arrange the following bonds in order of increasing polarity and identify the shift of the electrons: C – N, O – H, and H – Cl.
Bond EN
C - N C
N 3.0
O – H
O 3.5
H 2.1
H - Cl
Cl 3.0

14. Electronegativity and Bonds
Without using the numbers in the electronegativity scale, determine which would be more ionic LiF or BF3?